Single layer resists have been the main stream approach for optical lithography. To extend 248 nm optical lithography down to the sub-200 nm regime, high performance resists are required.
One way to extend 248 nm optical lithography to the sub-200 nm regime is to reduce the thickness of the resist film. Another way is to use various wave front engineering techniques, such as phase shift masks. These approaches place stringent lithographic and etch requirements on the single layer resist. These requirements include sub-200 nm resolution, good profile, high etch resistance for bottom ARC (antireflective coating) and substrate etching, and compatibility with phase shift mask technology.
Unfortunately, prior art resists are unable to meet all of these requirements due to several deficiencies which exist with the same. These deficiencies include poor resist profile due to excessive top loss, particularly at small dimensions, and insufficient etch resistance in substrate etch as a result of resist loss during opening of the underlying ARC material. Moreover, the prior art resists tend to give rise to unwanted side slopes when attenuated phase shift masks are used.
Resist compositions containing silicon either in the main resist polymer or by post-exposure surface treatment (e.g., silylation) have either failed to deliver adequate improvement in etch resistance, have had poor processing performance and/or require expensive or undesired process steps.
In view of the deficiencies with prior art resists, there is a need for a resist composition which provides, among other things, high image resolution, good process windows and excellent etch resistance.